Self-tapping screw

Abstract

A self-tapping screw includes a head, a shank provided on the head and threads provided on the shank, wherein the threads include a first contact surface and a second contact surface forming a thread angle of 40 degrees therebetween. A vertical line from a vertex of the thread angle is drawn perpendicular to the shank, and the first contact surface forms a first inclination angle with the vertical line, and the second contact surface forms a second inclination angle with the vertical line, wherein the first inclination angle is different from the second inclination angle. The present invention can be used to replace mechanical screws as it has a smaller assembly torque suitable for fastening onto lighter objects.

1 . A self-tapping screw comprising a head, a shank provided on the head and threads provided on the shank, wherein the threads include a first contact surface and a second contact surface forming a thread angle of 40 degrees therebetween. 
     
     
         2 . The self-tapping screw of  claim 1 , wherein a vertical line from a vertex of the thread angle is drawn perpendicular to the shank, and the first contact surface forms a first inclination angle with the vertical line, and the second contact surface forms a second inclination angle with the vertical line, wherein the first inclination angle is different from the second inclination angle. 
     
     
         3 . The self-tapping screw of  claim 1  or  2 , wherein the first inclination angle is larger than the second inclination angle. 
     
     
         4 . The self-tapping screw of  claim 3 , wherein the first inclination angle is 25 degrees and the second inclination angle is 15 degrees. 
     
     
         5 . The self-tapping screw of  claim 3 , wherein a pitch between the threads is between 0.2 mm to 0.35 mm, and a depth of the threads is between 0.8 mm to 5.0 mm.